无模式文档反应器？

class ExtDocReactor : public AcApDocManagerReactor 
{
private:
  CPaletteBlockChildDlg *mpDlg;
public:
  ExtDocReactor (CPaletteBlockChildDlg *dlg):mpDlg(dlg){
    acDocManager->addReactor (this) ;
  }
  ~ExtDocReactor () {
    if ( acDocManager != NULL )
      acDocManager->removeReactor (this);
  }
  virtual void documentActivated(AcApDocument* pActivatedDoc) {
    if(mpDlg)
      mpDlg->OnDocumentActivated(pActivatedDoc);
  }
};

CPaletteBlockChildDlg::CPaletteBlockChildDlg (CWnd *pParent /*=NULL*/, HINSTANCE hInstance /*=NULL*/) 
: CAcUiDialog (CPaletteBlockChildDlg::IDD, pParent, hInstance)
{
  //{{AFX_DATA_INIT(CPaletteBlockChildDlg)
  mExtDocReactor = new ExtDocReactor(this);
  m_locale = _get_current_locale();
  //}}AFX_DATA_INIT
}